$use-prefixes: true;
$theme: "dark" body{
  @if $theme == dark {
    background-color: black;
  } @else if ($theme == light) {
    background-color: #ccc;
  } @else {
    background-color: grey;
  }

}

.rounded {
  @if $use-prefixes {
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
  }

}
